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  • override delete function in entity framework

    - by k0ni
    How can i make my own delete method to prevent that the data really gets deleted? i want to set a datetime field when it gets deleted insted of a normal delete. i read about overriding the submitchanges function, but i don't get it to work thanks

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  • How to create relationship between two tables with revisions using Entity Framework

    - by Chris Ridenour
    So I am in the process of redesigning a small database (and potentially a much larger one) but want to show the value of using revisions / history of the business objects. I am switching the data from Access to MSSQL 2008. I am having a lot of internal debate on what version of "revision history" to use in the design itself - and thought I had decided to add a "RevisionId" to all tables. With this design - adding a RevisionId to all tables we would like tracked - what would be the best way to create Navigational Properties and Relationships between two tables such as | Vendor | VendorContact | where a Vendor can have multiple contacts. The Contacts themselves will be under revision. Will it require custom extensions or am I over thinking this? Thanks in advance.

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  • DeleteObject method is missing in Entity Framework 4.1

    - by bobetko
    This is driving me crazy. I am getting error that object doesn't contain definition for DeleteObject. Here is my line of code that produces an error: ctx.Tanks.DeleteObject(Tank); I tried to reference another object from another edmx file that my friend has created and then everything is fine, DeleteObject exists. I don't think I miss any references in my project. And project itself contains edmx file and I used DBContext to create POCOs. Any ideas?

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  • Missing something with Entity Framework for .NET 3.5?

    - by AC
    Is it not possible to have EF create the necessary entities when I have two related tables linked with a FK in .NET3.5SP1? I see where the checkbox to support this is disabled but it is available in .NET4. I've got a DB that has only tables with relationships in it. I need to build a Silverlight app (SL4) that allows management of the data within this app. I can't use .NET4 on the server... only .NET3.5SP1 so FK relationship bit in EF4 isn't available to me. Looking to avoid building as much of the plumbing to get back to the DB from the SL4 app as possible...

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  • Entity Framework 4 - Delete Object

    - by GibboK
    I have 3 Tables in my DataBase CmsMasterPages CmsMasterPagesAdvSlots (Pure Juction Table) CmsAdvSlots Here a Picture of my EDM: I need find out all objects CmsAdvSlot connected with a CmsMasterPage (it is working in my code posted belove), and DELETE the result (CmsAdvSlot) from the DataBase. My Problem is I am not able to DELETE this Objects when I found theme. Error: The object cannot be deleted because it was not found in the ObjectStateManager. int findMasterPageId = Convert.ToInt32(uxMasterPagesListSelector.SelectedValue); CmsMasterPage myMasterPage = context.CmsMasterPages.FirstOrDefault(x => x.MasterPageId == findMasterPageId); var resultAdvSlots = myMasterPage.CmsAdvSlots; // It is working until here foreach (var toDeleteAdv in resultAdvSlots) { context.DeleteObject(myMasterPage.CmsAdvSlots.Any()); // ERORR HERE!! context.SaveChanges(); } Any idea how to solve it? Thanks for your time! :-)

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  • Entity Framework 5 upgrade from 4

    - by user1714591
    I'm having an issue with the Where clause in a search, in my original version EF4 I could add a Where clause with 2 parameters, the where clause (string predicate) and a ObjectParameter list such as var query = context.entities.Where(WhereClause.ToString(), Params.ToArray()); since my upgrade to EF5 I don't seem to have that option am I missing something? This was originally used to build dynamic where clause such as "it.entity_id = @entity_id" then holding the variable value in the ObjectParameter. I'm hoping I don't have to rewrite all the searches that have been built out this way, so any assistance would be greatly appreciated. Cheers

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  • Entity Framework 4.0 GetChanges() equivalent

    - by Jonathan
    Hi In LINQ to SQL, you can override SubmitChanges and use the method this.GetChangeSet() to get all the inserts, updates and deletes so that you can make last minute changes before it is committed to the database. Can this be done in EF 4.0? I see there is a override for SaveChanges but I need to know the equivalent for GetChangeSet()

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  • How to get around the Circular Reference issue with JSON and Entity

    - by DanScan
    I have been experimenting with creating a website that leverages MVC with JSON for my presentation layer and Entity framework for data model/database. My Issue comes into play with serializing my Model objects into JSON. I am using the code first method to create my database. When doing the code first method a one to many relationship (parent/child) requires the child to have a reference back to the parent. (Example code my be a typo but you get the picture) class parent { public List<child> Children{get;set;} public int Id{get;set;} } class child { public int ParentId{get;set;} [ForeignKey("ParentId")] public parent MyParent{get;set;} public string name{get;set;} } When returning a "parent" object via a JsonResult a circular reference error is thrown because "child" has a property of class parent. I have tried the ScriptIgnore attribute but I lose the ability to look at the child objects. I will need to display information in a parent child view at some point. I have tried to make base classes for both parent and child that do not have a circular reference. Unfortunately when I attempt to send the baseParent and baseChild these are read by the JSON Parser as their derived classes (I am pretty sure this concept is escaping me). Base.baseParent basep = (Base.baseParent)parent; return Json(basep, JsonRequestBehavior.AllowGet); The one solution I have come up with is to create "View" Models. I create simple versions of the database models that do not include the reference to the parent class. These view models each have method to return the Database Version and a constructor that takes the database model as a parameter (viewmodel.name = databasemodel.name). This method seems forced although it works. NOTE:I am posting here because I think this is more discussion worthy. I could leverage a different design pattern to over come this issue or it could be as simple as using a different attribute on my model. In my searching I have not seen a good method to overcome this problem. My end goal would be to have a nice MVC application that heavily leverages JSON for communicating with the server and displaying data. While maintaining a consistant model across layers (or as best as I can come up with).

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  • Entity Framework - Self Tracking Objects - how to reset client side?

    - by David
    I am using wcf with self tracking entity framework objects. On the client side i have bound an entity to an edit form (which has multiple textboxes and comboboxes). After the user hits Save, the entity is sent through wcf to the server wcf service which will attempt to save the entity. If there is a failure (say a network failure), I need to reset the current entity back to original values. How best can I do this client side? (I recognize with Self Tracking objects there is a property OriginalValues however that collection seems to have count=0) so not sure how to get the original values? Thanks-

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  • Extracting the Date from a DateTime in Entity Framework 4 and LINQ

    - by Ken Cox [MVP]
    In my current ASP.NET 4 project, I’m displaying dates in a GridDateTimeColumn of Telerik’s ASP.NET Radgrid control. I don’t care about the time stuff, so my DataFormatString shows only the date bits: <telerik:GridDateTimeColumn FilterControlWidth="100px"   DataField="DateCreated" HeaderText="Created"    SortExpression="DateCreated" ReadOnly="True"    UniqueName="DateCreated" PickerType="DatePicker"    DataFormatString="{0:dd MMM yy}"> My problem was that I couldn’t get the built-in column filtering (it uses Telerik’s DatePicker control) to behave.  The DatePicker assumes that the time is 00:00:00 but the data would have times like 09:22:21. So, when you select a date and apply the EqualTo filter, you get no results. You would get results if all the time portions were 00:00:00. In essence, I wanted my Entity Framework query to give the DatePicker what it wanted… a Date without the Time portion. Fortunately, EF4 provides the TruncateTime  function. After you include Imports System.Data.Objects.EntityFunctions You’ll find that your EF queries will accept the TruncateTime function. Here’s my routine: Protected Sub RadGrid1_NeedDataSource _     (ByVal source As Object, _      ByVal e As Telerik.Web.UI.GridNeedDataSourceEventArgs) _     Handles RadGrid1.NeedDataSource     Dim ent As New OfficeBookDBEntities1     Dim TopBOMs = From t In ent.TopBom, i In ent.Items _                   Where t.BusActivityID = busActivityID _       And i.BusActivityID And t.ItemID = i.RecordID _       Order By t.DateUpdated Descending _       Select New With {.TopBomID = t.TopBomID, .ItemID = t.ItemID, _                        .PartNumber = i.PartNumber, _                        .Description = i.Description, .Notes = t.Notes, _                        .DateCreated = TruncateTime(t.DateCreated), _                        .DateUpdated = TruncateTime(t.DateUpdated)}     RadGrid1.DataSource = TopBOMs End Sub Now when I select March 14, 2011 on the DatePicker, the filter doesn’t stumble on time values that don’t make sense. Full Disclosure: Telerik gives me (and other developer MVPs) free copies of their suite.

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  • Entity Framework 4.0: Creating objects of correct type when using lazy loading

    - by DigiMortal
    In my posting about Entity Framework 4.0 and POCOs I introduced lazy loading in EF applications. EF uses proxy classes for lazy loading and this means we have new types in that come and go dynamically in runtime. We don’t have these types available when we write code but we cannot forget that EF may expect us to use dynamically generated types. In this posting I will give you simple hint how to use correct types in your code. The background of lazy loading and proxy classes As a first thing I will explain you in short what is proxy class. Business classes when designed correctly have no knowledge about their birth and death – they don’t know how they are created and they don’t know how their data is persisted. This is the responsibility of object runtime. When we use lazy loading we need a little bit different classes that know how to load data for properties when code accesses the property first time. As we cannot add this functionality to our business classes (they may be stored through more than one data access technology or by more than one Data Access Layer (DAL)) we create proxy classes that extend our business classes. If we have class called Product and product has lazy loaded property called Customer then we need proxy class, let’s say ProductProxy, that has same public signature as Product so we can use it INSTEAD OF product in our code. ProductProxy overrides Customer property. If customer is not asked then customer is null. But if we ask for Customer property then overridden property of ProductProxy loads it from database. This is how lazy loading works. Problem – two types for same thing As lazy loading may introduce dynamically generated proxy types we don’t know in our application code which type is returned. We cannot be sure that we have Product not ProductProxy returned. This leads us to the following question: how can we create Product of correct type if we don’t know the correct type? In EF solution is simple. Solution – use factory methods If you are using repositories and you are not using factories (imho it is pretty pointless with mapper) you can add factory methods to your EF based repositories. Take a look at this class. public class Event {     public int ID { get; set; }     public string Title { get; set; }     public string Location { get; set; }     public virtual Party Organizer { get; set; }     public DateTime Date { get; set; } } We have virtual member called Organizer. This property is virtual because we want to use lazy loading on this class so Organizer is loaded only when we ask it. EF provides us with method called CreateObject<T>(). CreateObject<T>() is member of ObjectContext class and it creates the object based on given type. In runtime proxy type for Event is created for us automatically and when we call CreateObject<T>() for Event it returns as object of Event proxy type. The factory method for events repository is as follows. public Event CreateEvent() {     var evt = _context.CreateObject<Event>();     return evt; } And we are done. Instead of creating factory classes we created factory methods that guarantee that created objects are of correct type. Conclusion Although lazy loading introduces some new objects we cannot use at design time because they live only in runtime we can write code without worrying about exact implementation type of object. This holds true until we have clean code and we don’t make any decisions based on object type. EF4.0 provides us with very simple factory method that create and return objects of correct type. All we had to do was adding factory methods to our repositories.

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  • Is it possible to auto update only selected properties on an existent entity object without touching the others

    - by LaserBeak
    Say I have a bunch of boolean properties on my entity class public bool isActive etc. Values which will be manipulated by setting check boxes in a web application. I will ONLY be posting back the one changed name/value pair and the primary key at a time, say { isActive : true , NewsPageID: 34 } and the default model binder will create a NewsPage object with only those two properties set. Now if I run the below code it will not only update the values for the properties that have been set on the NewsPage object created by the model binder but of course also attempt to null all the other non set values for the existent entity object because they are not set on NewsPage object created by the model binder. Is it possible to somehow tell entity framework not to look at the properties that are set to null and attempt to persist those changes back to the retrieved entity object and hence database ? Perhaps there's some code I can write that will only utilize the non-null values and their property names on the NewsPage object created by model binder and only attempt to update those particular properties ? [HttpPost] public PartialViewResult SaveNews(NewsPage Np) { Np.ModifyDate = DateTime.Now; _db.NewsPages.Attach(Np); _db.ObjectStateManager.ChangeObjectState(Np, System.Data.EntityState.Modified); _db.SaveChanges(); _db.Dispose(); return PartialView("MonthNewsData"); } I can of course do something like below, but I have a feeling it's not the optimal solution. Especially considering that I have like 6 boolean properties that I need to set. [HttpPost] public PartialViewResult SaveNews(int NewsPageID, bool isActive, bool isOnFrontPage) { if (isActive != null) { //Get entity and update this property } if (isOnFontPage != null) { //Get entity and update this property } }

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  • Is component-based design an architectural pattern or design pattern?

    - by xEnOn
    When using the component-based paradigm in game development with engines like Unity, is component-based design an architectural pattern, or a design pattern? Can I even say that component-based design is my "main" architectural pattern for my game? I see architectural patterns as being more high-level than design pattern. The component-based design in game development's context (like with Unity engine) seems to fit as an architectural pattern to me. However, on some sites, I read that component-based design is a behavioural pattern, much like other behavioural design patterns, and not so much like an architectural pattern like MVC.

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  • How do I communicate with an IronPython component in a C#/XNA game?

    - by Jonathan Hobbs
    My XNA game is component-oriented, and has various components for position, physics representation, rendering, etc, all of which extend a base Component class. The player and enemies also have controllers which are currently defined in C#. I'd like to turn them into Python scripts, but I'm not sure how to interact with those scripts. The examples in Embedding IronPython in a C# Application suggest I'd have to create a wrapper class (e.g. a Script component) which compiles a Python script, and call the Update methods of the component in the script Is this the most effective way of working with a Python object? I feel that I'm missing something in my research - there must be a way to load up a script, instantiate a Python object and then work directly with it from within C#. Or is the wrapper required?

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  • How to implement a component based system for items in a web game.

    - by Landstander
    Reading several other questions and answers on using a component based system to define items I want to use one for the items and spells in a web game written in PHP. I'm just stuck on the implementation. I'm going to use a DB schema suggested in this series (part 5 describes the schema); http://t-machine.org/index.php/2007/09/03/entity-systems-are-the-future-of-mmog-development-part-1/ This means I'll have an items table with generic item properties, a table listing all of the components for an item and finally records in each component table used to make up the item. Assuming I can select the first two together in a single query, I'm still going to do N queries for each component type. I'm kind of fine with this because I can cache the data into memcache and check there first before doing any queries. I'll need to build up the items on every request they are used in so the implementation needs to be on the lean side even if they're pulled from memcache. But right there is where I feel confident about implementing a component system for my items ends. I figure I'd need to bring attributes and behaviors into the container from each component it uses. I'm just not sure how to do that effectively and not end up writing a lot of specialized code to deal with each component. For example an AttackComponent might need to know how to filter targets inside of a battle context and also maybe provide an attack behavior. That same item might also have a UsableComponent which allows the item to be used and apply some effect onto a different set of targets filtered differently from the same battle context. Then not every part of an item is an active part, an AttributeBonusComponent might need to only kick in when the item is in an equipped state or when displaying the item details page. Ultimately, how should I bring all of the components together into the container so when I use an item as a weapon I get the correct list of targets? Know when a weapon can also be used as an item? Or to apply the bonuses the item provides to a character object? I feel like I've gone too far down the rabbit hole and I can't grasp onto the simple solution in front of me. (If that makes any sense at all.) Likewise if I were to implement the best answer from here I feel like I'd have a lot of the same questions. How to model multiple "uses" (e.g. weapon) for usable-inventory/object/items (e.g. katana) within a relational database.

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  • Getting ClassCastException with JSF 1.2 Custom Component and BEA 10.3

    - by Tobi
    Im getting a ClassCastException if i use Attributes in my Custom Headline Tag. Without Attributes rendering works fine. Calling <t:headline value="test" /> gives a ClassCastException even before a Method in my HeadlineComponent or HeadlineTag-Class is called. <t:headline /> works fine. I'm using MyFaces-1.2, on BEA 10.3 default.jsp <%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%> <%@ taglib prefix="f" uri="http://java.sun.com/jsf/core"%> <%@ taglib prefix="h" uri="http://java.sun.com/jsf/html"%> <%@ taglib prefix="t" uri="http://www.tobi.de/taglibrary" %> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> <title>Tobi Test</title> </head> <body> <f:view> <t:headline value="test" /> </f:view> </body> </html> HeadlineComponent.java package tobi.web.component.headline; import java.io.IOException; import javax.el.ValueExpression; import javax.faces.component.UIOutput; import javax.faces.context.FacesContext; import javax.faces.context.ResponseWriter; public class HeadlineComponent extends UIOutput { private String value; private Integer size; @Override public Object saveState(FacesContext context) { Object values[] = new Object[3]; values[0] = super.saveState(context); values[1] = value; values[2] = size; return ((Object)(values)); } @Override public void restoreState(FacesContext context, Object state) { Object values[] = (Object[])state; super.restoreState(context, values[0]); value = (String)values[1]; size = (Integer)values[2]; } @Override public void encodeBegin(FacesContext context) throws IOException { // Wenn keine Groesse angegeben wurde default 3 String htmlTag = (size == null) ? "h3" : "h"+getSize().toString(); ResponseWriter writer = context.getResponseWriter(); writer.startElement(htmlTag, this); if(value == null) { writer.write(""); } else { writer.write(value); } writer.endElement(htmlTag); writer.flush(); } public String getValue() { if(value != null) { return value; } ValueExpression ve = getValueExpression("value"); if(ve != null) { return (String)ve.getValue(getFacesContext().getELContext()); } return null; } public void setValue(String value) { this.value = value; } public Integer getSize() { if(size != null) { return size; } ValueExpression ve = getValueExpression("size"); if(ve != null) { return (Integer)ve.getValue(getFacesContext().getELContext()); } return null; } public void setSize(Integer size) { if(size>6) size = 6; if(size<1) size = 1; this.size = size; } } HeadlineTag.java package tobi.web.component.headline; import javax.el.ValueExpression; import javax.faces.component.UIComponent; import javax.faces.webapp.UIComponentELTag; public class HeadlineTag extends UIComponentELTag { private ValueExpression value; private ValueExpression size; @Override public String getComponentType() { return "tobi.headline"; } @Override public String getRendererType() { // null, da wir hier keinen eigenen Render benutzen return null; } protected void setProperties(UIComponent component) { super.setProperties(component); HeadlineComponent headline = (HeadlineComponent)component; if(value != null) { if(value.isLiteralText()) { headline.getAttributes().put("value", value.getExpressionString()); } else { headline.setValueExpression("value", value); } } if(size != null) { if(size.isLiteralText()) { headline.getAttributes().put("size", size.getExpressionString()); } else { headline.setValueExpression("size", size); } } } @Override public void release() { super.release(); this.value = null; this.size = null; } public ValueExpression getValue() { return value; } public void setValue(ValueExpression value) { this.value = value; } public ValueExpression getSize() { return size; } public void setSize(ValueExpression size) { this.size = size; } } taglibrary.tld <?xml version="1.0" encoding="UTF-8" ?> <taglib xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-jsptaglibrary_2_1.xsd" version="2.1"> <description>Tobi Webclient Taglibrary</description> <tlib-version>1.0</tlib-version> <short-name>tobi-taglibrary</short-name> <uri>http://www.tobi.de/taglibrary</uri> <tag> <description>Eine Überschrift im HTML-Stil</description> <name>headline</name> <tag-class>tobi.web.component.headline.HeadlineTag</tag-class> <body-content>empty</body-content> <attribute> <description>Der Text der Überschrift</description> <name>value</name> <required>false</required> <rtexprvalue>true</rtexprvalue> </attribute> <attribute> <description>Die Größe der Überschrift nach HTML (h1 - h6)</description> <name>size</name> <required>false</required> <rtexprvalue>true</rtexprvalue> </attribute> </tag> </taglib> faces-config.xml <?xml version="1.0" encoding="UTF-8"?> <faces-config xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-facesconfig_1_2.xsd" version="1.2"> <component> <description>Erzeugt eine Überschrift nach HTML-Stil</description> <display-name>headline</display-name> <component-type>tobi.headline</component-type> <component-class>tobi.web.component.headline.HeadlineComponent</component-class> <attribute> <attribute-name>value</attribute-name> <attribute-class>java.lang.String</attribute-class> </attribute> <attribute> <attribute-name>size</attribute-name> <attribute-class>java.lang.Integer</attribute-class> <default-value>3</default-value> </attribute> </component> </faces-config>

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  • Executing logic before save or validation with EF Code-First Models

    - by Ryan Norbauer
    I'm still getting accustomed to EF Code First, having spent years working with the Ruby ORM, ActiveRecord. ActiveRecord used to have all sorts of callbacks like before_validation and before_save, where it was possible to modify the object before it would be sent off to the data layer. I am wondering if there is an equivalent technique in EF Code First object modeling. I know how to set object members at the time of instantiation, of course, (to set default values and so forth) but sometimes you need to intervene at different moments in the object lifecycle. To use a slightly contrived example, say I have a join table linking Authors and Plays, represented with a corresponding Authoring object: public class Authoring { public int ID { get; set; } [Required] public int Position { get; set; } [Required] public virtual Play Play { get; set; } [Required] public virtual Author Author { get; set; } } where Position represents a zero-indexed ordering of the Authors associated to a given Play. (You might have a single "South Pacific" Play with two authors: a "Rodgers" author with a Position 0 and a "Hammerstein" author with a Position 1.) Let's say I wanted to create a method that, before saving away an Authoring record, it checked to see if there were any existing authors for the Play to which it was associated. If no, it set the Position to 0. If yes, it would find set the Position of the highest value associated with that Play and increment by one. Where would I implement such logic within an EF code first model layer? And, in other cases, what if I wanted to massage data in code before it is checked for validation errors? Basically, I'm looking for an equivalent to the Rails lifecycle hooks mentioned above, or some way to fake it at least. :)

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  • Effective way to check if an Entity/Player enters a region/trigger

    - by Chris
    I was wondering how multiplayer games detect if you enter a special region. Let's assume there is a huge map that is so big that simply checking it would become a huge performance issue. I've seen bukkit (a modding API for Minecraft servers) firing an Event on every single move. I don't think that larger games do the same because even if you have only a few coordinates you are interested in, you have to loop through a few trigger zone to see if the player is inside your region - for every player. This seems like an extremely CPU-intense operation to me even though I've never developed something like that. Is there a special algorithm that is used by larger games to accomplish this? The only thing I could imagine is to split up the world into multiple parts and to register the event not on the movement itself but on all the parts that are covered by your area and only check for areas that are registered in the current part. And another thing I would like to know: How could you detect when someone must have entered a trigger but you never saw him directly in it since his client only sent you an move packet shortly before entering and after leaving the trigger area. Drawing a line and calculate all colliding parts seems rather CPU intensive if you have to perform it every time.

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  • Loading Entities Dynamically with Entity Framework

    - by Ricardo Peres
    Sometimes we may be faced with the need to load entities dynamically, that is, knowing their Type and the value(s) for the property(ies) representing the primary key. One way to achieve this is by using the following extension methods for ObjectContext (which can be obtained from a DbContext, of course): 1: public static class ObjectContextExtensions 2: { 3: public static Object Load(this ObjectContext ctx, Type type, params Object [] ids) 4: { 5: Object p = null; 6:  7: EntityType ospaceType = ctx.MetadataWorkspace.GetItems<EntityType>(DataSpace.OSpace).SingleOrDefault(x => x.FullName == type.FullName); 8:  9: List<String> idProperties = ospaceType.KeyMembers.Select(k => k.Name).ToList(); 10:  11: List<EntityKeyMember> members = new List<EntityKeyMember>(); 12:  13: EntitySetBase collection = ctx.MetadataWorkspace.GetEntityContainer(ctx.DefaultContainerName, DataSpace.CSpace).BaseEntitySets.Where(x => x.ElementType.FullName == type.FullName).Single(); 14:  15: for (Int32 i = 0; i < ids.Length; ++i) 16: { 17: members.Add(new EntityKeyMember(idProperties[i], ids[i])); 18: } 19:  20: EntityKey key = new EntityKey(String.Concat(ctx.DefaultContainerName, ".", collection.Name), members); 21:  22: if (ctx.TryGetObjectByKey(key, out p) == true) 23: { 24: return (p); 25: } 26:  27: return (p); 28: } 29:  30: public static T Load<T>(this ObjectContext ctx, params Object[] ids) 31: { 32: return ((T)Load(ctx, typeof(T), ids)); 33: } 34: } This will work with both single-property primary keys or with multiple, but you will have to supply each of the corresponding values in the appropriate order. Hope you find this useful!

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  • hibernate empty collection in component

    - by Jurgen H
    I have a component mapped using Hibernate. If all fields in the component in the database are null, the component itself is set to null by hibernate. This is the expected behavior and also what I need. The problem I have, is that when I add a bag to that component, the bag is initialized to an empty list. This means the component has a non null value... resulting in the component being created. Any idea how to fix this? <class name="foo.bar.Entity" table="Entity"> <id name="id" column="id"> <generator class="native" /> </id> <property name="departure" column="departure_time" /> <property name="arrival" column="arrival_time" /> <component name="statistics"> <bag name="linkStatistics" lazy="false" cascade="all" > <key column="entity_id" not-null="true" /> <one-to-many class="foo.bar.LinkStatistics" /> </bag> <property name="loggedTime" column="logged_time" /> ... </component> A criteria with Restirctions.isNull("statistics") does return the expected values.

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  • A Simple Entity Tagger

    - by Elton Stoneman
    In the REST world, ETags are your gateway to performance boosts by letting clients cache responses. In the non-REST world, you may also want to add an ETag to an entity definition inside a traditional service contract – think of a scenario where a consumer persists its own representation of your entity, and wants to keep it in sync. Rather than load every entity by ID and check for changes, the consumer can send in a set of linked IDs and ETags, and you can return only the entities where the current ETag is different from the consumer’s version.  If your entity is a projection from various sources, you may not have a persistent ETag, so you need an efficient way to generate an ETag which is deterministic, so an entity with the same state always generates the same ETag. I have an implementation for a generic ETag generator on GitHub here: EntityTagger code sample. The essence is simple - we get the entity, serialize it and build a hash from the serialized value. Any changes to either the state or the structure of the entity will result in a different hash. To use it, just call SetETag, passing your populated object and a Func<> which acts as an accessor to the ETag property: EntityTagger.SetETag(user, x => x.ETag); The implementation is all in at 80 lines of code, which is all pretty straightforward: var eTagProperty = AsPropertyInfo(eTagPropertyAccessor); var originalETag = eTagProperty.GetValue(entity, null); try { ResetETag(entity, eTagPropertyAccessor); string json; var serializer = new DataContractJsonSerializer(entity.GetType()); using (var stream = new MemoryStream()) { serializer.WriteObject(stream, entity); json = Encoding.UTF8.GetString(stream.GetBuffer(), 0, (int)stream.Length); } var guid = GetDeterministicGuid(json); eTagProperty.SetValue(entity, guid.ToString(), null); //... There are a couple of helper methods to check if the object has changed since the ETag value was last set, and to reset the ETag. This implementation uses JSON to do the serializing rather than XML. Benefit - should be marginally more efficient as your hashing a much smaller serialized string; downside, JSON doesn't include namespaces or class names at the root level, so if you have two classes with the exact same structure but different names, then instances which have the same content will have the same ETag. You may want that behaviour, but change to use the XML DataContractSerializer if you think that will be an issue. If you can persist the ETag somewhere, it will save you server processing to load up the entity, but that will only apply to scenarios where you can reliably invalidate your ETag (e.g. if you control all the entry points where entity contents can be updated, then you can calculate and persist the new ETag with each update).

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  • Building Tag Cloud Declarative ADF Component

    - by Arunkumar Ramamoorthy
    When building a website, there could a requirement to add a tag cloud to let the users know the popular tags (or terms) used in the site. In this blog, we would build a simple declarative component to be used as tag cloud in the page. To start with, we would first create the declarative component, which could display the tag cloud. We will do that by creating a new custom application from the new gallery. Give a name for the app and the project and from the new gallery, let us create a new ADF Declarative Component We need to specify the name for the declarative component, attributes in it etc. as follows For displaying the tags as cloud, we need to pass the content to this component. So, we will create an attribute to hold the values for the tag. Let us name it as "value" and make it as java.lang.String  type. Once after this, to hold the component, we need to create a tag library. This can be done by clicking on the Add Tag Library button. Clicking on OK buttons in all the open dialogs would create a declarative component for us. Now, we need to display the tag cloud based on the value passed to the component. To do that, we assume that the value is a Tree Binding and has two attributes in it, say "Name" and "Weight". To make a tag cloud, we would put together the "Name" in a loop and set it's font size based on the "Weight". After putting our logic to work, here is how the source look Attributes added to the declarative components can be retrieved by using #{attrs.<attribute_name>}. Now, we need to deploy this project as ADF Library Jar file, so that this can be distributed to the consuming applications. We'll select ADF Library Jar as type and create the profile. We would be getting the jar file after deployment. To test the functionality, we could create a simple Fusion Web Application. To add our custom component to the consuming application, we can create a file system connection pointing to the location where the jar file is and add it or, add through the project properties of the ViewController project. Now, our custom component has been added to the consuming application. We could test that by creating a VO in the model project with a query like, select 'Faces' as Name,25 as Weight from dual union all select 'ADF', 15 from dual  union all select 'ADFdi', 30 from dual union all select 'BC4J', 20 from dual union all select 'EJB', 40 from dual union all select 'WS', 35 from dual Add this VO to the AppModule, so that it would be exposed to the data control. Then, we could create a jspx page, and add a tree binding to the VO created. We can now see our Tag Cloud declarative component is available in the component palette.  It can be inserted from the component palette to our page and set it's value property to CollectionModel of the tree binding created. Now that we've created the Declarative component and added that to our page successfully, we can run the page to see how it looks. As per the query, the Tags are displayed in different fonts, based on their weight.

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  • How to extend abstract Entity class in RIA Services

    - by Calanus
    I want to add a bool variable and property to the base Entity class in my RIA services project so that it is available throughout all the entity objects but seem unable to work out how to do this. I know that adding properties to actual entities themselves is easy using .shared.cs and partial classes but adding such properties to the Entity class using similar methods doesn't work. For example, the following code doesn't work namespace System.ServiceModel.DomainServices.Client { public abstract partial class Entity { private bool auditRequired; public bool AuditRequired { get { return auditRequired; } set { auditRequired = value; } } } } All that happens is that the existing Entity class gets totally overriden rather than extending the Entity class. How do I extend the base Entity class so that functionality is available thoughout all derived entity classes?

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  • Register Game Object Components in Game Subsystems? (Component-based Game Object design)

    - by topright
    I'm creating a component-based game object system. Some tips: GameObject is simply a list of Components. There are GameSubsystems. For example, rendering, physics etc. Each GameSubsystem contains pointers to some of Components. GameSubsystem is a very powerful and flexible abstraction: it represents any slice (or aspect) of the game world. There is a need in a mechanism of registering Components in GameSubsystems (when GameObject is created and composed). There are 4 approaches: 1: Chain of responsibility pattern. Every Component is offered to every GameSubsystem. GameSubsystem makes a decision which Components to register (and how to organize them). For example, GameSubsystemRender can register Renderable Components. pro. Components know nothing about how they are used. Low coupling. A. We can add new GameSubsystem. For example, let's add GameSubsystemTitles that registers all ComponentTitle and guarantees that every title is unique and provides interface to quering objects by title. Of course, ComponentTitle should not be rewrited or inherited in this case. B. We can reorganize existing GameSubsystems. For example, GameSubsystemAudio, GameSubsystemRender, GameSubsystemParticleEmmiter can be merged into GameSubsystemSpatial (to place all audio, emmiter, render Components in the same hierarchy and use parent-relative transforms). con. Every-to-every check. Very innefficient. con. Subsystems know about Components. 2: Each Subsystem searches for Components of specific types. pro. Better performance than in Approach 1. con. Subsystems still know about Components. 3: Component registers itself in GameSubsystem(s). We know at compile-time that there is a GameSubsystemRenderer, so let's ComponentImageRender will call something like GameSubsystemRenderer::register(ComponentRenderBase*). pro. Performance. No unnecessary checks as in Approach 1. con. Components are badly coupled with GameSubsystems. 4: Mediator pattern. GameState (that contains GameSubsystems) can implement registerComponent(Component*). pro. Components and GameSubystems know nothing about each other. con. In C++ it would look like ugly and slow typeid-switch. Questions: Which approach is better and mostly used in component-based design? What Practice says? Any suggestions about implementation of Approach 4? Thank you.

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